Permanent magnetic assisted synchronous reluctance motor as a new-style permanent magnet motor combines advantages of the permanent magnet motor and the synchronous reluctance motor, and has advantages of high power density, wide speed adjustable range, high efficiency, small volume, and etc., thus has a bright application prospect. A formula of the electromagnetic torque of the permanent magnetic assisted synchronous reluctance motor is as follows:T=mp(Lq-Ld)idiq+mpψPMiq.
In the above formula, T is an output torque of a motor, the performance of the motor can be improved by increasing the value of T; the first item in the equation following T is the reluctance torque, and the second item is the permanent magnet torque; ψPM is the maximum value of stator-rotor coupling magnetic flux generated by a permanent magnet of the motor, m is a phase number of a conductor of a stator, Ld and Lq are inductances along axis d and axis q respectively, wherein axis d refers to an axis coincided with an axis of the main magnetic pole, and axis q refers to an axis perpendicular to the axis of the main magnetic pole, the perpendicular relationship refers to perpendicularity of electrical angles, and id and iq are components of an armature current in the directions of axis d and axis q respectively.
In the prior art, the performance of the motor is generally improved by improving the performance of the permanent magnet, that is, by increasing the permanent magnet torque to increase the value of the resultant torque so as to improve the efficiency of the motor, and the common method is to use rare-earth permanent magnets. However, since rare earth is a non-renewable resource and is expensive, the widespread use of this kind of motor is restricted. Additionally, the urgent demand of further improving the motor efficiency can not be met by only improving the performance of the permanent magnet. Further, if the permanent magnet is inserted into the motor, a tensile deformation or even a fracture may happen at the edge of the rotor operated at high speed.